1. Field of the Invention
This invention relates to an oil burner which controls combustion and fire extinguishing by means of vertical movements of a wick.
2. Description of the Prior Art
An oil burner which controls combustion and fire extinguishing by means of vertical movements of a wick is generally provided with a burner portion 2 on a tank 1, as shown in FIGS. 7 to 10. A wick 3 which is constantly urged downwardly is provided in the burner portion 2 to be vertically movable through a rack 5 and a pinion 6 by a wick shaft 4. A ratchet 9 is mounted on the wick shaft 4 through friction members 10, 11, and a retainer 8 is secured to the wick shaft 4. A rotary plate 13 with a pin 14 is attached to the retainer 8 and a through hole 15 is formed in the ratchet 9 at a position corresponding with the pin 14.
The pin 14 is passed through the through hole 15 to enable vertical movements of the wick 13 within the range of the through hole 15 or controlling the extent of combustion as well as preventing incomplete combustion due to excessive descent of the wick 13. A vibration sensor 16 is attached to the tank 1. The vibration sensor 16 comprises a weight 17, an extinguishing knob 18 and a lever 19 which is operated by the weight 17 and the extinguishing knob 18. A latch portion 20 at the end of the lever 19 is adapted to engage with a tooth 9' of the ratchet 9 so as to prevent the ratchet 9 from rotating in the wick lowering direction. The ratchet 9 is able to rotate until the protrusion 9" provided on the ratchet 9 abuts against the latch portion 20; in other words, the maximum angle of rotation of the ratchet 9 is determined to be one rotation and the wick 3 moves vertically within this range. A knob 21 is fixed to the wick shaft 4.
In an oil stove as described above, when the knob 21 is rotated in the wick elevating direction, the wick 3 is elevated while accumulating force through the rack 5 and the pinion 6. At this time, the ratchet 9 is caused by means of the frictional force of the friction members 10, 11 to rotate together with the wick shaft 4. When the operating force applied on the ratchet 9, and thus the operating force applied on the knob 21 is released, the tooth 9' is retained by the latch portion 20 and the wick 3 is maintained at a predetermined level. In controlling the level of the wick 3, the knob 21 is rotated in the wick lowering direction (opposite to the wick elevating direction), whereby the wick shaft 4 can rotate together with the friction members 10, 11 in against the frictional force thereof, while the ratchet 9 can not be rotated due to its engagement with the latch portion 20 of the lever 19. In this way, the level of the wick is controlled within the range of the through hole 15 within which the pin 14 is movable.
In lowering the wick for extinguishment in the normal state, the engagement of the tooth 9' with the latch portion 20 is released by the operation of the lever 19 at a touch to the extinguishing knob lever 18, whereby the stored force of the wick 3 is released and the wick 3 rapidly descends to the lowermost position to immediately extinguish a flame in a very simple and convenient operation. On the other hand, in unusual circumstances, for example, when an earthquake happens during use, the weight 17 detects this and operates the lever 19. Accordingly, the wick 3 rapidly descends to the lowermost position in a similar manner to the extinguishing operation of the extinguishing knob 18, whereby immediate extinguishment is effected.
The conventional oil stove described above is very suitable for countries having regulations according to which the level of a wick must be positively stopped at a predetermined position, and must not be lower than a predetermined position by the same operation (hereinunder referred to as "one-touch extinguishment system") in order to safely maintain the charactaristics of exhaust gases, temperatures and the like. On the other hand, the knob 21 for vertically moving the wick permits the wick 3 to descend within the range of the through hole 15 formed in the ratchet 9, and further descent of the wick can not be performed except for the case where fire extinguishing is performed in rapid descent of the wick by the operation of the extinguishing knob 18. For this reason, in oil-limited countries where a mixture of different kinds of fuels such as fuel containing much heavy gravity constituent or light oil is used, tar or the like is produced at the end of the wick 3 such that accumulation of tar or the like cancels or overcomes the reserving descent force of the wick to prevent descent of the wick. Moreover, when the wick 3 is caught at a position where fire extinguishing is impossible, burning continues to be very dangerous even if the user tries to extinguish the fire by the onetouch operation of the extinguishing knob 18. In order to extinguish the fire in this case, it is necessary to manually turn the knob 21 with the extinguishing knob 18 operated, namely the engagement of the latch portion 20 by the tooth 9' is released. This operation is very difficult to understand and perform particularly when attempted in an emergency when the fire has not been successfully extinguished.
In these countries, greater importance is attached to durability of a wick and safe fire extinguishing than to such convenience as is offered by the one-touch fire extinguishing system. So, a structure in which fire extinguishing is ensured by rotating the knob 21 by hand, (hereinunder referred to as "manual fire extinguishing system") has been in demand since a user can put forth his strength.
An example of an oil burner which affords the above-described manual fire extinguishing is shown in FIGS. 11 and 12, and is put to practical use. In FIGS. 11 and 12, the reference numeral 23 denotes a vertically movable wick, 23a a wick holder integrally attached to the wick 23, 24 a rack member integrally secured to the wick holder 23a, and 24a a rack which is formed in the circumferential direction of the oil burner and is inclined relative to the horizontal, as shown in FIG. 12. The reference numeral 25 represents a wick shaft for vertically moving the wick 23, and 26 a pinion which is provided on the forward end of the wick shaft 25 and is intermeshed with the rack 24a of the rack member 24. Thus rotation of the wick shaft 25 elevates the wick 23 while rotating it through the pinion 26 and the rack 24a. The wick shaft 25 is slidable in the axial direction and is urged toward the wick holder 23a by a spring 27. The wick holder 23a is formed with a resilient cutaway protrusion 28 which is disposed on the path of contacting movement of the forward end 25a of the wick shaft 25. In the state where the wick 23 is lowered, one end 24a' of the rack 24a is meshed with the pinion 26 of the wick shaft 25, as shown by an imaginary line in FIG. 11.
When the wick shaft 25 is rotated in this state, engagement of the rack 24a with the pinion 26 causes, the rack member 24 to be rotated and elevated. As the wick shaft 25 is rotated even after the cutaway protrusion 28 of the wick holder 23a comes into contact with the forward end 25a of the wick shaft 25, the cutaway protrusion 28 is deformed toward the wick and passes the forward end 25a of the wick shaft 25, until the other end 24a" of the rack 24a abuts against the pinion 26, and is stopped. Thus, the wick 23 is elevated to the uppermost position. When the wick shaft 25 is rotated in the revese direction from this position in order to control combustion, the cutaway protrusion 28 of the wick holder 23a abuts against the forward end 25a of the wick shaft 25, as shown by the solid line in FIG. 11, and further rotation of the wick shaft 25 is restrained. In other words, the wick 23 is restrained from lowering further. In order to further lower the wick 23 for the purpose of fire extinguishing, the wick shaft 24 is rotated while being pulled toward the user against the bias of the spring 27 so that the cutaway protrusion 28 disengages from the forward end 25a of the wick shaft 25.
As described above, this oil burner can stop the wick at a predetermined level without fail as well as enabling a manual extinguishment by releasing the stopping.
However, this oil burner is disadvantageous in that it can not be applied to an anti-earthquake extinguishment device which is adapted to lower the wick upon detection of vibration by a vibration sensor used in combination with the device. More specifically, when actuation of the vibration sensor permits the spring 27 to apply its bias on the wick shaft 25 for rotation in the wick descending direction, the cutaway protrusion 28 of the wick holder 23a abuts against the forward end 25a of the wick shaft 25 and is stopped at the lower end of the range in which the level of the wick is controlled, whereby the wick shaft 25 can not be lowered to the level of extinguishment.
As described above, in the prior art, there has not been proposed any structure, in which a range for use is definitely limited to prevent further rotation of a wick shaft beyond the lower limit, and in which such limitations are made ineffective by a simple operation to afford fire extinguishing by manual rotation of the wick and lowering the wick to a level for fire extinguishing by operation of an anti-earthquake extinguishment device.